Alkylation of hydrocarbons



Sept. 3, 1,946. A.' CLARKE A LKYLATION OF HYDROCARBONS Filed Deo. 24, 1942 2 Sheets-Sheet lA Sept '3, 1946 L. A. CLARKE ALKYLATIO OF HYDROCRBONS Filed Deo-L 24, 1942 2 Sheets-Sheet 2 FIG. 3

Louls A. CLARKE l Patented Sept. 3, `1946 ALKYLATION OF HYDROCARBONS `Louis A. Clarke, Fishkill, N. Y., assignor to The Texas Company, New York,

tion of Delaware N; Y., va corpora- Application December 24, 1942, Serial No.'470,043 l This invention relates to alkylation for the production of motor fuel hydrocarbons of high antiknock value, and more particularly to the alkylation of paraiiin hydrocarbons with olefms or other suitable alkylating agents in the presence of a liquid alkylation catalyst.

One of the principal objects of the invention is to provide an improved method of carrying out this alkylation reaction to obtain large yields of high quality alkylate withgood catalyst life while avoiding emulsion and settling difficulties, eliminating or minimizing corrosion difliculties and effecting economy in power consumption.

Still another object of the invention is to provide novel and improved apparatus for carrying out this alkylation reaction and accomplishing the above noted advantages, the apparatus being simple in construction and of low initial and maintenance cost.

'Other objects and advantages of the invention will be Vapparent from the following description when taken in conjunction with the accompanying drawings and appended claims.

Heretofore, alkylation of an isoparafn with an olefin has been carried out commercially in several diiierent types of equipment or reactors. One generally used type is the so-called pump and time tank reactor wherein the feed hydrocarbons are introduced at the suction side of a pump into an emulsion recycle stream of mixed catalyst and hydrocarbon, the stream being forced With turbulent flow through a suitable chiller and then into a time tank which usually contains suitable baiiies or other means for preventing breaking of the emulsion. A substantial prcportion of the stream Withdrawn from the time tank is recycled to the recirculating pump while a minor proportion is withdrawn for recovery of alkylate. f While this type of equipment functions very satisfactorily with certain catalysts, particularly sulfuric acid, difficulties are encountered When it is attempted to adapt that equipment to a liquid catalyst containing suspended solid material, such as an aluminum halide-hydrocarboncomplex containing added aluminum halide, due to clogging of the lines and other causes, Moreover, the power requirements for operating the pump are material; and corrosion diiiiculties of the moving parts of the pump, the pump packing and other parts are experienced with certain-highly corrosive catalysts, such as hydrofluoricacid. l

Another type of equipment which has` been usedcommercially for alkylation and operates upon this generalprinciple ofemulsion recycle 9 Claims. (Cl. BSO-683.4)

is the so-called mixer of the turbo type which utilizes internal recirculation of emulsion at very high velocity. The power requirements for this type of apparatus are substantial, and other objections and difficulties with certain types of catalysts, as noted above, are encountered.

A third type of apparatus which has been used commercially for this alkylation reaction is the so-called -jet reactor wherein the hydrocarbon and catalyst are pumped under high pressure and introduced through a jet or thimble having a plurality of ports into the catalyst-hydrocarbon mixture so as to produce substantial agitation and emulsication of the contents of the reactor. In this form, emulsion is withdrawn through an overflow, a minor portion being passed to' a suitable settler, and a major portion of the emulsion `being recycled to the jet.` This type of equipment retains all the disadvantagesnoted above.

The present invention provides a novel reactor which is generally applicableto the varioustypes oi liquid alkylation catalysts. The expression liquid alkylation catalyst is used throughout the Vdescription and claims tomean a material which is fluid and pumpable even though it may contain dissolved or suspended solids orgases. This includes among others a pure liquid such as anhydrous hydrofluoric acid, a liquid containing dissolved gas or other liquid such as hydrofluoric acid `containing 'dissolved boron iluoride, and `a liquid containing iinely divided suspended matter but which is fluid and pumpable, such as aluminum halide-hydrocarbon complex containing suspended aluminum halide. Moreover, by means of the novel method of this invention, emulsion and settling difficulties are avoided, corrosion and erosion of parts, such as pumps and pump packings, are effectively eliminated, and economy may be effected in power consumption.

In accordance with the present invention, the liquid alkylation catalyst is maintained as a relatively stationary body in the continuous phase in a vertical reactor of substantial height, such as a tower, and a `mixed feed of paraffin hydrocarbon and oleiin or other alkylating agent in liquid phase, with the paraflin in substantial molar excess of the alkylating agent, is introduced through a small orifice or a plurality of orifices into the lower portion of the liquid cata-V lyst body. Asa matter of convenience, the invention is described hereinafter in connection with the use of olefin as the alkylating agent, but it is to be understood that other alkylating agents can berused in place of the olefin, as more particularly pointed outhereinbelow.' The mixed feed passes through the oriiice or orifices in such a manner that the feed liquid is dispersed in fine drops in the continuous catalyst phase.

The liquid alkylation catalyst has a higher speciiic gravity than the mixed paraiiin hydrocarbon and olefin employed, whereby the dispersed drops of hydrocarbon mixture rise upwardly through the body of liquid catalyst due to this diiference in gravity. While there is some turbulence of the liquid catalyst body adjacent the point or points of introduction of the hydrocarbon mixture, there is insuicient agitation to form an emulsion. By the expression emulsion is meant the intimate mixture of subdivided particles of both catalyst and hydrocarbon heretofore produced in alkylation reactions of this character by mechanically driven stirrers, high capacity pumps producing turbulent iiow, or agitating jets which produce eflcient mixing and movement of the catalyst along with the hydrocarbon through the reaction zone.v Such an emulsion resists breaking in the reaction zone or reactor and is passed from the reactor into a relatively quiescent zone of a settler, where sufficient settling time is allowed for separate catalyst and hydrocarbon phases to be formed. In the present case, the hydrocarbon mix passes into the maintained body of catalyst liquid in the form of dispersed drops without emulsiiication. Even though there may bea localized disturbance of the lower portion of the continuous catalyst phase due to the higher velocity of the hydrocarbon adjacent the locus of introduction, the liquid catalyst remains as ra continuous phase. The dispersed drops of hydrocarbon rise upwardly through the tower without rcorresponding upward movement of the catalyst liquid. The net result is 'that the hydrocarbon mix passes in dispersed form upwardly through a relatively stationary continuous catalyst phase, and promptly forms a separate and superposed hydrocarbon layer as it reaches the top or upper surface of the catalyst liquid.

As distinguished from the prior practice in this art, wherein highly eicient agitation with the formation of emulsion was considered a prime requisite for the production of vhigh yields of alkylate of good quality, it has now been 'discovered that such emulsion-forming agitation can be avoided while 'still obtaining the desired results .by utilizing the principles of the present invention. .As :stated above, the liquid catalyst is relatively unagitated except for Vsuch turbulence and liquid ilow as results from the introduction of the reactants, and the movement of the dispersed drops of reactants upwardly through the maintained body of catalyst liquid. There is substantially*unidirectional flow of the hydrocarbon or `reactant phase upwardly through the relatively stationary `continuous catalyst phase. Also, the orifice is of such small size, generally having a `diameter of about ,de vinch to l inch, and is so correlated with the through-put, that the hydro.- carbon Vreactants are dispersed in the form of small drops of various sizes not exceed-ing about 1A; inch in diameter, and preferably' much smaller so as .t have a large .surf/ace area to volume ratio. This aords a :large Iarea vof contact between the outer lm of each Ydrop and the surrounding catalyst liquid. This operation has been found to promote the desired alkylation reaction between the paraflin and the olelin present in the dispersed drops as the latter pass upwardly through the substantial height of continuous catalyst phase.

As the drops of Ymixed alkylate and unreac'ted hydrocarbon reach the upper surface of the catalyst body, they coalesce to form a superposed hydrocarbon layer. A distinct interface between the liquid catalyst body and the superposed hydrocarbon layer is generally maintained in the upper portion of the tower. A stream of this hydrocarbon layer overows through a discharge line in accordance with the feed rate to the tower.

It is found with some catalysts that the dispersed hydrocarbon drops may tend to entrap a small amount of the catalyst liquid in this superposed hydrocarbon layer. Since the rate of rise of the dispersed drops of hydrocarbon through the catalyst is relatively slow, a considerable volurne of dispersed hydrocarbon is normally present at any one time in the catalyst liquid, so that the interface level in the tower during operation is substantially above the initial level of the catalyst alone, Moreover, accidental or deliberate iiuctuations in the throughput may cause the interface level to vary; and increase in throughput `may cause the level to reach the point of stream withdrawal. Further, the tower can be satisfactorily operated with the interface level at the stream withdrawal point so that the catalyst continuously overflows along with hydrocarbon. In order to `insure that catalyst thus carried over with hydrocarbon does not pass into the neutralizing and fractionating sections of the unit, a separator or trap is provided adjacent the point of stream withdrawal and preferably at about the level thereof. Since such catalyst as is entrapped in the superposed hydrocarbon layer or overflows through the stream withdrawal is not in the form of an emulsion with the hydrocarbon, it immediately, or at least rapidly, drops out in this separator, so that large .settling volume with substantial settling time is not required as in the case of an emulsion. However, the trap or separator can be constructed -of substantial volume, when hydrocarbon recycle is employed, to function as a reservoir for the circulating hydrocarbon. All or any portion of this trapped-out catalyst is preferably returned to the maintained catalyst body within the tower, together with such make-up catalyst as may be required. In continuous operation, a portion of Athis catalyst may be intermittently or continuously discharged from the system to recovery, and fresh catalyst introduced to make up for that withdrawn The recycle .of .settled hydrocarbon unmixed with acid or other catalyst to the alkylation reaction zone has 'heretofore been proposed in connection with reactors operating with eiilcient agitation and th'e formation of emulsions. However, this requires very extensive settling volume, particularly where the recycle rate is many times the Vfresh feed rate. Consequently, such hydrocarbon recycle has not proved commercially attractive, and emulsion recycle has been universally employed. While a once-through operation is feasible in the present reactor, it is found that materially improved results can be .secured in many cases by recycling hydrocarbon to the reaction Zone. Preferably a high recycle ratio of the order of about 10 to ll'volumes or more of hydrocarbon recycle to 1 volume of fresh feed is employed. This materially increases the ratio of paraffin `to olefin in the reaction zone and increases the eifective time of contact, as is well known. Since the settling is quite rapid or a1- most instantaneous in the present-operation, it is apparent that the diiiiculties inherent in previous proposalsl involving recycle of hydrocarbon separated from an emulsion Aare effectively over'- 4packed tower.

come. The recycled hydrocarbon is preferably first admixed with the fresh feed hydrocarbon, and themixture introduced through' the orifice or orices into the reaction zone. The trappedout catalyst is preferably returned directly and by gravity to the maintained catalyst body, thereby avoiding the use of pumps in the handling of the more corrosive catalyst liquid.

If desired, the reactor or tower of the present invention may be supplied in the reaction zone with one or more layers of solid contact or filling material to thereby increase the length of the path of flow and th'e time of contact for each once-through flow of the dispersed drops in the catalyst liquid. The packed tower can be operated withonce-through flow or hydrocarbon recycle. Any suitable contact material, which is non-reactive with respect to the catalyst and the reactants and which provides sufficient free space for the proper travel of the drops, may be employed. A very suitable type of material for this purpose consists ofsmall contact pieces, each shaped to simulate a saddle, and known to the trade as berl saddles. There is some indication that the use of a packing in the tower may enable the use of somewhat larger size drops and obtain as good results as with a higher degree of dispersion (i. e., smaller size drops) in an un- Moreover, the combination of a packed tower with a high degree of dispersion can be used. i However, very satisfactory results Vare secured with an unpacked tower operating with either Yonce-through' flow or hydrocarbon recycle, preferably the latter.

Any of the conventional catalytic alkylation reactions can be carried out by the method and with the apparatus of the present invention.

Thus, the reaction of an isop'araffin with an ole- .n or other alkylating agent, as well as the alkylation of a normal parafn with an olefin or other 'alkylating agent, in the presence of suitable alkylation catalysts can be accomplished. Th'e 'paraffin charge stock may be either normally gaseous or normally liquid or a mixture thereof. In isoparafiin alkylation, isobutane and isopentane are preferred, although it is to be under- `stood that any of the low boiling isoparains may be used and conventional catalysts effective for such isoparaiiin alkylation can be employed.` The present invention appears particularly effecf vtive for isoparain alkylation with hydroiiuoric acid or aluminum chloride-hydrocarbon complex `containing suspended aluminum chloride as the catalyst. Likewise normal paraflins can be alkylated with olei'lns or other alkylating agents in the Vpresence of suitable catalysts, such' as hydrogen uoride containing dissolved boron triiiuoride or aluminum chloride-hydrocarbon complex' containing suspended aluminum chloride.

Various normally gaseous or liquid normal paraf-` ns, such as normal butane, normal pentane and -higher normal paraffins or mixtures thereof, may

be used for the charge stock. Likewise, mixtures of visoparaffns and normal paraffins may be employed. 'I'he features of tower type alkylation of the present character, as applied to isobutaneethylene with an activated aluminum chloridehydrocarbon complex catalyst, is disclosed land claimed in the copending application of Louis A.

Clarke, Serial N0. 535,261, flled May 12, 1944.

Vas di-isobutylene and tri-isobutylene, cross polyl mersV of isobutylene and normal butylene, mixed or non-selective Ca-C4 polymers, and the like, and various fractions of thermally or catalytically cracked gasolines and of polymer naphthas may be used.

In place of an olefin as-the alkylating agent, various alcohols and ethers, such as isopropyl alcohol, tertiary butyl alcohol, secondary butyl alcohol, isopropyl ether and the like, may be employed with suitable known alkylation catalysts which' have tolerance for water liberated in the reaction. Likewise, the corresponding alkyl esters, such as the alkyl halides, sulfates, phosphates, etc. of the olens, may be used as the alkylating agent with an appropriate or compatible alkylation catalyst, as is well known.

vWherever the expression alkylating agent is used throughout the description and claims, it will be understood that this refers to olens as well as alcohols, ethers and esters of the character described above and which are capable of reacting with a paraflin or other hydrocarbon having a replaceable hydrogen atom to produce an alkylated hydrocarbon of higher molecular weight of the character set forth herein.

Any ofthe well known conditions suitable for the various alkylation reactions can be used. In general, a substantial molar excess of paraffin to olefin or other alkylating agent is employed, such as a `feed ratio in excess of 1:1 and preferably about 4:1 to 8:1, which provides a substantially higher contact ratio in the reaction zone generally inl excess of about 50:1 when hydrocarbon recycle is used. The reactor is maintained under sufficient pressure to linsurethat the hydrocarbons and alkylating agents are in the liquid phase. The temperature of the reac-V tion varies with the hydrocarbons or alkylating agents employed and with the catalyst, as is well understood, but generally ranges from about F. to about 150 F. A high ratio of catalyst to hydrocarbon is inherently maintained in the reaction zone due to the maintained body of catalyst liquid of substantial height through which the hydrocarbon phase is dispersed. As pointed out above, the present invention departs radically from the previous practice in this art with respect to agitation, since mechanical stirrers and high capacity pumps with eincient agitation are avoided, and introduction of dispersed hydrocarbon `without the formation of an emulsion and the risingof hydrocarbon drops through the relatively stationary body of continuous catalystV phase by the difference in gravity therebetween,

are substituted.A

The invention is more particularly illustrated in the attached drawings which disclose preferred embodiments thereof. In the drawings:

Fig. 1 is a diagrammatic illustration of appa- 'ratus suitable for carrying out the method of the present invention;

plate of Fig.

' olefin in liquid phase is introduced by pump 9 through pipe I0 controlled by valve Il into the bottom of tower `I2 beneath the orifice plate I3. .The `tower may be equipped with an external jacket I provided with inlet IB and outlet I1 for the supply of a suitable cooling or heating medium to maintain the desired temperature within the reaction zone. It is to be understood that other conventional means for controlling the temperature in the reaction zone can be used, such as the fresh feed and recycle hydrocarbon chiller hereinafter described, internal evaporative cooling, etc. As shown more particularly in Fig. 2, the tower is partially filled with a suitable liquid catalyst I8. The amount of catalyst liquid is generally such that,l during operation with an appreciable volume of hydrocarbon liquid dispersed` in the Catalyst at any one time, the interface I9 between the relatively stationary body of liquid catalyst and the superposed hydrocarbon layer is positioned adjacent the upper end ofthe tower.

The orice plate I3 is provided with an opening or orifice 22 shown as positioned at the vertical axis of the tower, this orifice being of small size of the order previously indicated. The entire tower is maintained under sufficient pressure so that the hydrocarbon mix ysupplied by line I0 is in liquid phase, and this mix is under sufi-lcient additional pressure to counter-balance the height of the liquid column within the tower and to overcome the pressure drop through orifice 22 to obtain the desired dispersion. The space 23 in the tower beneath the orifice plate I3 remains filled with the hydrocarbon mix, and the catalyst liquid is prevented from flowing down through the orifice. into this space and backing up into theinlet pipe I0 by the maintained feed pressure. This causes the hydrocarbon to pass through orifice 22 with the formation of a multitude of small drops indicated at 24, which pass up through the liquid catalyst body due to the difference in gravity between the catalyst and the hydrocarbon. As the drops reach the interface I9, they coalesce to form the superposed hydrocarbon layer 20.

While the orifice plate i3 can be equipped with a simple opening in some cases, it is preferably provided with an upstanding nozzle 25 of a known type adapted to effect a spray dispersion of the hydrocarbon in the form of ne drops. For any given nozzle of this character, at the lower throughput or rate of supply of hydrocarbon, fewer drops of a larger size will issue from the opening or discharge orifice of the nozzle. Theoretically, the throughput rate can be reduced to the point where the drops issue one after the other in relatively slow succession, provided the orifice is sufficiently small so that each individual drop is of a proper small size. As the throughput rate is increased from this given orifice, the drops not only issue faster but are of smaller size. This also causes the level of the interface I9 to rise, due to the larger number of dispersed drops and the greater volume of hydrocarbon present in the liquid catalyst body at any one time. As the throughput is further increased, the drops become exceedingly fine and the interface level reaches a maximum height. Further increase of the throughput beyond this limit causes an accumulation of hydrocarbon to be formed within the base of the tower surrounding the nozzle, from which globs o-f the hydrocarbon break off and rise upwardly through the tower. This latter condition results in a drop in the interface level, due to the fact that the degree of dispersion and the quantity of hydrocarbon dispersed in the catalyst liquid at any one time is then reduced. Consequently, this last mentioned condition of operation, which is objectionable and is to be avoided, can be readily detected by the drop in interface level. While satisfactory operation can be secured at the lower throughputs described above, it is generally desirable to operate in. the upper portion of the throughput range which produces greater dispersion and a higher interface level approaching the upper limit described above.

Referring again to Fig. 1, the tower I2 is equipped with an overflow or outlet 26 through which the hydrocarbon layer 20 is discharged in a stream to a suitable separator or trap 21. AS shown, this is preferably a cylindrical vessel arranged with its longitudinal axis somewhat inclined to the horizontal. Adjacent the lower end of the separator, a bottom discharge line 28 is provided to conduct catalyst by gravity back to the lower portion of the tower. Pipe 28 opens into the tower at a locus 29 opposite the maintained catalyst body I8, so that this catalyst is returned directly thereto.

The upper end of separator 21' is also provided with an overflow 33 connected with branched lines 3l and 32 controlled by valves 3| and 32 respectively. Hydrocarbon may be passed to the alkylate discharge line 3| or a portion of the alkylate passed to the discharge line 3| and the balance to the hydrocarbon recycle line 32 containing a suitable pum-p 33. Line 32 communi- Cates with the hydrocarbon mix feed lineV I0, a suitable surge drum 34 being preferably connected to line 32 by branch line 34' in advance of pipe Ill to take care of fiuctuations in the pumping rate and to maintain the regulated pressure in the feed line Ill. Preferably, a'suitable chiller or heat exchanger 35 is positioned within line Iii' in advance of the tower inlet to precondition the temperature of the fresh feed hydrocarbon and the recycle hydrocarbon to maintain the desired temperature withinv the reaction zone of the tower. Any suitable control means can be used for regulating the pressure and rate of through-put of the fresh feed and hydrocarbon recycle through the orifice to thereby control and regulate the degree of dispersion of the drops in the catalyst liquid, such as the proportioning pumps 9 and 33 and the surge tank 34 as shown.

As pointed out above, a major portion of the hydrocarbon is preferably recycled through line 3? and re-introduced together with the fresh feed through line I0 into the tower. A minor proportion of the settled hydrocarbon is withdrawn in accordance with the fresh feed rate through pipe 3| and passed by pump 36 together with suitable neutralizing agent, such as caustic soda solution, introduced by line 31, into a scrubber 33 where the hydrocarbon is neutralized. The neutralized materiall overows by line 39 into an intermediate portion of a settler 49 where the caustic soda solution settles out and is withdrawn through line 4I. The bulk of the solution is recycled by line 42 to line 31 for reuse in treating fresh quantities of hydrocarbon, while a minor proportion may be withdrawn intermittently or continuously by a discharge line 43, fresh make-up caustic soda solution being added by feed line 44.

The neutralized and settled hydrocarbon overflows from settler 4I] through line 43 and is introduced by pump 41 into a stabilizer 48 where unreacted gases including excess paraffin are removed overhead by line 49. These lighter gases are forced by pump 50 into a suitable fractionator I where separation is made between unreacted isoparaiiin, such as isobutane, which is withdrawn by overhead line 52 for recycling to the reaction tower I2, and any heavier hydrocarbons such as normal butane, which are withdrawn by bottom line 53. It will be understood that the fractionating system shown is that particularly designed for isobutane alkylation wherein the charge, which may be a suitable refinery C4 cut, also contains normal butane. However, the fractionating system can modined from that 4shown in accordance with the charge stock being handled as is well understood in the art.

The stabilized alkylate is removed from the bottom of stabilizer 48 byline 55-and passed by pump 56 to a suitab-le fractionator 51 which serves to take overhead a desired fraction, such as an aviation fraction boiling up to about 350 to 375 F. A heavier residue fraction is removed by bottom discharge line 58. The o-verhead vaporized fraction passes by line 59 through a suitable condenser 60, and the condensed liquid flows by line 6I into an accumulator 62. Any light gases may :be bled off from accumulator 62 by vapor drawoff 63 and the desired stabilized fraction of the alkylate is removed by bottom line 64 to suitable blending tanks or storage (not shown). Y

yThe `reaction tower |'2 illustrated in Fig. 2 is of a relatively smaller capacity type having a single orifice 22. This tower may be conveniently constructed of an interior diameter of about one inchto 12 inches or more, with an oririce selected to give fine dispersion and a lateral distribution to substantially extend throughout the, cross-section thereof. The tower may be from about 5 feet to 20 feet or more in height.` It. will be understood that this is merely representative of satisfactory tower reactors having a single orifice, and that the invention is not limited to towers of these dimensions. However, for a single orice type, the height should be many times greater than the diameter. Such towers have ,been successfully operated -with heights of catalyst liquid varying from about 30 inches up to about 200 inches or more.

Where a plural number of oriiices are used, the diameter of the tower maybe greatly increased without necessarily increasing the height. The latter dimension is regulated in accordance with thecharge stocks and catalysts with a view to insuring substantially complete disappearance of the olen or other alkylating agent as such in a once-through passage. objectionable side reactions due to prolonged contact of hydrocarbon or unreacted olefin with catalyst in transfer linesA and settlers are minimized or avoided. It

is to be understood that two or more towers'can be used with series flow of hydrocarbon therethrough, where the desired degree of conversion or `reaction cannot be accomplished in a single tower of practical height. In this tower reactor, the time of contact for all portions of the react# ing hydrocarbons is uniform. v i

In Figures 3 and 4, there is shown a modifica-v tion of the tower reactor particularly designed for largerscale operation. In this form the tower 10 is of relatively larger'diameter, such as from two to six feet or more. A bottom orice plateV 12 is provided with a plurality of upstanding nozzles 1-3 arranged more or less uniformly over the cross section'of the plate. Eaohnozzle is constructed to provide effective dispersionin the manner previQuSly, descried; 'the Several mzzl@ .heini S0.'

10-Y spaced as to-substantially encompass` the crosssection of the towerwith the drops. This produces a series of sprays of drops 'l5 into the lower portion of the maintained liquid catalyst body, while avoiding undueagitation, and avoiding undue interference of the drops from one nozzle with those from another.'

Figure 5 dis closes another modification wherein thetower 86 is provided with a packing 8l of solid Contact material above the orifice plate 82. While a nozzle or plurality of nozzles can be'used in this form, it is foundthat with certain catalysts such as an aluminum chloride-hydrocarbon complex containing suspended aluminum chlo` ride a simple opening or orice 83 through lthe orifice plate functions satisfactorily to accomplish the desired dispersion and distribution of the hydrocarbon drops throughout the catalyst liquid, as aided by the contact material.

This packing may extend throughout substantially all of the contact zone containing the liquid catalyst, or may extend above .the orice plate 82 throughout only a portion of the height of the tower confining the catalyst, with an upper unpackedv Vthrough the free space provided by the packing,

the latter impeding the normal velocity of upward travel due to 4difference in gravity and increasing the length of the path of travel thereof.

While a nozzle, or a plurality of nozzles, adapted to direct the drops upwardly within the tower,

has been shown in the drawings, it is to be understood that this arrangement is not essential. Thus, the nozzle may be directed in an inclined or horizontal direction, so long as the hydrocarbon is dispersed into the catalyst liquid in the form of fine drops as described above, which are then free to rise through the catalyst liquid, and so long as undue agitation and emulsification are avoided. Moreover, it is to be understood that other types of dispersing devices can be employed, such as a cone adapted to introduce the hydrocarbon from the periphery thereof and thus disseminate the drops over a larger area of the cross-section of the tower.

The invention is further illustrated by the following specific examples; but it is to be understood that these are given by way of explanation and the invention is not limitedthereto.

Ercample I The Afollowing example illustrates the applica? tion of the invention to the alkylation of a mix-- ture of isobutane with a C4 fraction from a cracking operation, using anhydrous HF as the catalyst. The mixed hydrocarbon charge had the following analysis:

Weight percent The apparatus employed in the following runs included a `.tower constructed of one-inch steel tubing about seven feet .long equipped with a jacket through which cooling water was passed for thepurpose of controlling the temperature. The overflow from the tower was connected with aninclined separator made of copper which was two inches in diameter by seven feet long. The towerwas operated under two conditions, namely, packed for about iive feet of its height with brassplated steel jack chain and utilizing oncethrough operation for one continuous run, and unpacked with top separator recycle for a second continuous run. The volumetric characteristics of the tower were as follows:

cc. Volume of tower unpacked 1340 Free space in tower packed...v 1050 Free space in tower to top of packing 675 The tower was provided with an axially-arranged orifice et; inch in diameter.

In the run with the packed tower, the latter Was charged with 605 grams (605 cc.) of anhydrous liquid HF which nearlyl filled the packed portion thereof. The remainder of the system was then lled with isobutane, and the premixed charge, composed of a primary debutanizer overhead and commercial isobutane which had the above listed analysis, was charged into the bottom of the maintained catalyst body through the orice ata charge rate varying from 0.4 to 1.6 pounds per hour. The hydrocarbon mixture passed upwardly through the packed catalyst layer, and a stream of the superposed hydrocarbon layer was continuously Withdrawn to the separator, from which a top eiiiuent hydrocarbon stream was passed through a caustic scrubber, stabilized, distilled and tested.

Inthe run withY the unpacked tower employing top separator recycle, the tower was charged with 415 grams (415 cc.) of the anhydrous liquid HF and' the free space iilled with isobutane. Hydrocarbon fresh feed of the' same composition together with hydrocarbon recycle from the top of the settler were passed through the oriiice into the catalyst body, the fresh feed charge rate being 0.4 pound per hour and the recycle rate being 1.7 gallons perV hour. A stream from the hydrocarbon layer in the tower was passed to the separator, from which a major portion of the hydrocarbon was recycled to the fresh feed inlet while the remainder ywas passed through a caustic scrubber, stabilized, distilled and tested.

Each of the runs was continued vfor a period in excess of about 50 hours. The conditions and results of thel runs were as follows:

Packed Unpacked tower tower-top single separator pass recycle Charge rate, pounds per hour 0. 4-1. 6 0.4 Recycle rate, gallons per hou i None 1. 7 Temperature, F 70 70 Isobutane/oleiin mol ratio :1 5:1 Yield debutanized alkylate: i

Weight per cent on olefin .i 184 182 Volume per cent 311 F. E. P. fraction on basis of total debutanized alkylate 77 90 Volume per cent 2,2,4 trimethylpentane on basis of total debutanized alkylate 48 Octanenumber of 311 F.

E. nalkyme AFD 1C CFRM Clear 90.6 94.6. Plus l ce. TEL/ga1lon 97.1 IstIlzItJane-l-l-.ZG cc. Plus 3 cc. TEL/gallon Iso octane 0.14

cc. TEL. Plus 6 cc. TEL/gallon Iso-octauc|`l 98 cc.

TEL. f

' It was found in this work that the method and 12 apparatus of the present invention avoided hydrogen transfer reaction with the production of n-butane in the above noted C4 alkylation with HF. An analysis ofthe ofgas from the run with the unpacked tower listed above showedl the following:

Weight per cent Propane 1.3 Isobutane '75.7' Normal butane 21.6 Residue 1.4

Example II The following runs illustrate the alkylation of a normal paraln, such as normal butane, with an olen in the presence of a catalyst containing 510i Serial NO. 438,418, filed April 10, 1942. Briefly,

these conditions include a high normal parafnto-olen mol ratio, a catalyst consisting of HFv containing less than 46% by weight of BF: based on the weight of the mixed catalyst and gener- 'rally about 12-20%, a temperature within the range of 0-l50 F. with about 'l0-130 F. being preferred, a pressure of about -250 pounds per square inch, and a high catalyst to hydrocarbon ratio in the reaction zone. AS set forth in the said copending application noted immediately above, this. reaction not only eiTects alkylation of normal paraffin with olen but concomitantly effects isomerization or the production of a substantial yield of isobutane.

A series of continuous runs utilizing the HF- BFs catalyst for the alkylation of normal butane with various olens to produce alkylate and concomitantly form isobutane were carried out in accordance with the present invention in a stainless steel unpacked tower eight feet high and one inch inside diameter. The catalyst is highly corrosive to iron and ordinary steel; but copper, Monel metalv and I8-8 stainless steel satisfactorily resist corrosion. A convenient method of maintaining the required amount of BFs in the catalyst liquid, which was used in these runs, in volves Isaturating normal butane at room temperature and about pounds per square inch pressure with BFS; and introducing this normal butane saturated with BFa. together with a stream of mixed normal butane and olein through the orifice at the bottom of the tower into the. previously supplied catalyst liquid. 'Ihe tower was provided with a 1/8" diameter orifice. A brass tube two inches in diameter and seven feet long served as a separator.y

In starting up the` run, the system was lled to 200 pounds pressure with catalyst and. normal butane. Various heights of the maintained body of catalyst were employed in different. runs but in the runs listed below, a height of about 108- 109 was used with very satisfactory results. Topv separator recycle was employed, and catalyst was returned to the tower by gravity flow. The portion of the hydrocarbon 'not recycled was caustic neutralized, stabilized, fractionated and tested.

13T "I'he following are the conditions and results on two continuous runs of extended duration on normal butane-propylene and normal butaneethylene respectively: y Y

Olefin Propylene Ethylene 95. 6 96. 1 Bromine number 0r Octane number CFRM 83. 9 Residuerper cent by volume of total alk ate 4. 4 3. 9 Bromine number i 2 Volumesof alkylate per volume of catalyst. 12. 2+ 29. 2+ Isobutane:

Weight per cent yield basis normalbutane..v 27.1 40. 4 Weight per cent yield basis olefin 29 420 Weight per cent yield basis catalyslr.-. 974 l, 958

` In the, series of runs mentioned above, it was found that by increasing the height of the catalyst from 31 to 109 in normal butane-propylene alkylation employing hydrocarbon recycle, there was an increase in the yield off alkylate basis olefin, the percent of alkylate boiling below 311 F., the 4conversion of normal butane to isobu-tane and the catalyst life. Also, byV increasing the ratio of top settler recycle to fresh feed from `11.7 to 23.3, the yields and catalyst life were improved. Higher yields of alkylate and isobutane base-d on the olefin charged were obtained from normal butano-ethylene alkylation than from normal butane-propylene alkylation. q

While the invention has been described above in connection with the alkylation of paraffins with olefins or other lalkylating agents, it is alsocontemplated that Vthe method and apparatus of the present invention can be employed for thealkylation of other hydrocarbons having afreplac'eable hydrogen atom, such as aromatic and naphthene hydrocarbons, with olefins or other alkylating agents, 4such as alcoholsethers and esters. For example, the alkylation of benzene with propylene for the production of isopropyl benzene, the-alkylation of benzene with ethylene for the production of ethyl benzene, etc.,in the presence oflsuitable well known liquid catalysts which are immiscible with the hydrocarbon reactants, can be carried ,out in the manner and with the tower reactor vas described above. Y

`While in certain cases, the same liquid catalyst body as originally supplied tothe tower may be maintained therein for the entire reaction, thus providing continuous feed of hydrocarbon with batch feed of catalyst, it is to be understood that a portion of the liquid catalyst may be continuously or intermittently withdrawn and replaced with fresh catalyst during continuance of the process. By the expression relatively stationary as applied tov the'liquid catalyst body, it will be apparent that this signifies that the hydrocarbon moves relatively to the catalyst body and at a substantially greater rate or velocity, irrespective of such localized movement or turbulence which may exist within the catalyst liquid, particularly at the lower portion thereof. Moreover, itis to be understood that this expression includes operations in which a small portion of the catalyst liquid may continuously or intermittently overflow to the separator and be returned through the gravity line or in other suitable manner to the liquid catalyst confined within the tower, as Well as an operation in which a portion of the 114i catalystliquid may be continuously or intermittently withdrawn from a lowerV` or intermediate portion of the tower, and fresh catalyst liquid supplied to the maintained catalyst body con-` tinuously or intermittently at an upper or inter-` mediate portion of the tower. Thus, there may be relatively slow and progressive movement of the catalyst liquid downwardly through the tower countercurrent to the upwardly rising drops of.

hydrocarbon, the latter of course moving at a substantially higher velocity than the velocity of movement of the catalyst. In such event, the dispersed hydrocarbon drops are still appropriately described as rising upwardly through a relatively stationary body of the catalyst liquid, and this expression is used as a matter of convenience throughout the description and claims to include these various operations as above described.

It is therefore seen that, in accordance with the present invention, the necessity for handling` and recycling catalyst, oran emulsion containing catalyst, by high capacity pumps or other moving parts is avoided. The recycle of hydrocarbonvunmixed with catalyst can be accomvplislied without corrosion or erosion difficulties.

' The tower itself and other parts such as the separator and lines which contact the catalyst can readily be constructed of corrosion-resistant material; and the `more highly corrosive catalystY does not come in contact with movingv parts,` pump packings and the like. y

It has heretofore been proposed to effect ab,- sorption or polymerization of olens by dispersing the oleins in liquid phase through nozzles into aA body of sulfuric acid. However, it is well recognized that such reactions take place readily without efficient agitation. It has also been proposed to apply this operation to a refinery C4 cut from which isobutylene had been removed,

and which contained both isobutane and nbu.

tylenes with the latter in molar excess, in the presence of strong H2SO4 of at least 87%, for the absorption of n-butylenes in the acid and the concomitant production of a small yield of gasoline hydrocarbons of an unsaturated character.

It has not been heretofore recognized and taught that, in accordance with the method of the present invention, and by avoiding eiiicient agitation producing an emulsion, alkylation of a hydrocarbon or paraflin with an olefin or other alkylating agent could be accomplished as the principal reaction of the process, with minimum olen absorption and/or polymerization, whereby a substantially saturated alkylate of good quality is'obtained with minimum catalyst deterioration and resultant long catalyst life. This was unexpected and directly contrary to the previous knowledge and experience in this alkylation art. As pointed out above, this invention is particularly advantageous for those alkylation catalysts which are morecorrosive to pump parts and packings than sulfuric acid, such as I-IF, vlilik-Bib., BFanI-IZO,

om with an alkylating agent in the presence of an alkylation catalyst of greater specific gravity than the hydrocarbon and alkylating agent, which comprises maintaining an undispersedl liquidbody ofv the alkylation catalyst of substantial height as the continuous phase in a reaction zone, continuously dispersing a fresh feed of mixed hydrocarbon and alkylating agent substantially free from alkylation catalyst and with the hydrocarbon in liquid phase i-nto a lower por-V tion of the liquid catalyst body Without dispersion of the latter to form-a multitude of ne liquid drops of mixed hydrocarbon and alkylating agent which rise in dispersed form through a substantial height of the continuous catalyst phase due tol difference in gravity therebetween, whereby alkylation of the hydrocarbon with the alkylat ing agent to form normal-ly liquid alkylate takes place as the principal reaction of the process, the dispersed drops coalescing to form a hydrocar-v bon phase upon reaching the upper surface of' the liquid catalyst body, continuously removing a stream containing the coalesced hydrocarbon phase, settling any entrained catalyst from thev removed stream to provide a hydrocarbon layer substantially free from catalyst, recycling a major portion of the hydrocarbon layer containing alkylate and substantially free from catalyst and mixing the same with the fresh feed for redispersion unmixed with alkylation catalyst into the lower portion of the catalyst body, recovering a substantially saturated hydrocarbon alkylate from a minor portion of said hydrocarbon layer, and adding fresh alkylation catalyst directly to the maintained body without premixing with said fresh feed as the operation proceeds to preserve the alkylating activity thereof.

2. The method according to claim 1-J whereinthe said hydrocarbon is a low-boiling isoparailin and the alkylating agent isan olefin, and the liquid catalyst comprises hydroiluoric acid.

3. The method according to claim l, wherein the said hydrocarbon is a normal paran and the al-kylating agent is an olefin, and the liquid catalyst consists essentially of a major proportion of substantiallyanhydrous hydrofluoric acidcontaining a minor proportion of boron fluoride.

4. The method according tov claim l, whereinl the rate of throughput of fresh feed and. recycled hydrocarbon producesa dispersion of a large number of dropseach of less tha-n 1A; inch in diameter throughout the liquid* catalyst body giving a substantial rise in the operating levelY of the interface between the catalyst liquidi and the superposed hydrocarbon layer above the initial level of the catalyst body alone, the said. rate being below that: which causes an accumu-y lation of the fresh feed and' recycle liquid immediatel'y about the region of dispersion inthe lower portion of the reaction zone` resulting in a. reduction in the degree. of dispersion of the dropsi anda lowering of theinterface level.

5. The method according to claim 1, wherein at least a portion of the settled catalyst is returned directly to the maintained catalyst body without previous mixing with the fresh feed and recycled hydrocarbon dispersed into the lower portion of the catalyst body.

6. The method according to claim 1, wherein the hydrocarbon is a paraiiin, and the alkylating agent is an olen.

'7. The method according to claim 1,. wherein: the movement of the dispersed liquid drops rising through the liquid catalyst body in the reaction zone is modified and increased in length by contact with packing material submerged within the liquid catalyst body.

8. The method of continuously alkylating a hydrocarbon having a replaceable hydrogen atom with an alkylating agent in the presence of an `alkylation catalyst of greater specific gravity than the hydrocarbon and alkylatingv agent, which comprises maintaining an undispersed liquid body of the alkylation catalyst of substantial height as the continuous phase in a reaction zone, continuously dispersing a fresh feed of mixed hydrocarbon and alkylating agent substantially free from alkylation catalyst and with the hydrocarbon in liquid phase into a lower portion of the liquid catalyst body without dispersion of the latter to form a multitude of ne liquid drops ofi mixed hydrocarbon and alkylating agent which rise in dispersed form through a substantial height of the continuous catalyst phase due to difference in gravity therebetween, whereby alkylation of the hydrocarbon with the alkylating agent to form normally liquid alkylate takes place as the principa1 reaction of the process, the dispersed drops coalescingV to form a hydrocarbon phase upon reaching the upper surface of the liquid catalyst body, continuously removing from substantially at the level of the interface between the upper surface of the continuous catalyst body and the lower surface of the coalesced hydrocarbon phase a stream containing coalesced hydrocarbons along with some overflow catalyst liquid, rapidly separating catalyst liquid from the removed stream to provide a hydrocarbon layer substantially free from catalyst, removing a stream of the hydrocarbon layer and recovering a substantially saturated hydrocarbon alkylate therefrom, and adding alkyl'ation catalyst directly to the.- maintained catalyst body without premixing with said fresh feed as the operation proceeds to maintain the volume and alkylating activity of the said catalyst body.

9. The method according to claim 8, wherein atleast a portion of the settled catalyst together with fresh make-up catalyst is returned' directly to the maintained catalyst body without previous mixing with the fresh feed at a level near the lower portionY of the maintained catalyst body.

LOUIS A. CLARKE. 

